This could easily be the spark to ignite WW3. If Hezbollah joins in it’s on like donkey kong. That’s why many Western countries are trying to discourage Israel from any ground activities in Gaza. If they go in it’s almost certain Hezbollah will react and that could incite Jihad in the neighboring Arab countries which could easily get out of control.
There are elements in Israel that want to attack Lebanon, Syria and even Iran, as well as Gaza. Supposedly the delay is the internal dispute in the Israel War Cabinet over whether they just attack Gaza (Bibi) or attack Gaza and Hezbollah in Lebanon.
One of the things about the start of WW1 was that there was a “war party” in every country. It was stronger in Germany, but it was there in all of them.
All they needed was a trigger (in that case Russian mobilization) to give them the internal influence to start the general war.
There are so many ways that any attack now can escalate into a multi front war - maybe it is overdetermined.